Remote volume control board incl. 4 source selector, using relay (Halcro also use relay on their DA10 pre amp) switching two set of 1/4W RA resistor (made in USA - ladder network).
1dB per step, attenuate from 0dB to -88dB, input impedance is near constant, using 1/4W RAresistors, with four input relay and display, seperated voltage regulator board, with remote control handset, dual mono design, left and right channel fine adjustment.